Novel pyrotechnics



as we 3,122,462 NOVEL PYROTECHNICS Martin H. Kaufman, 411-A Nimitz,China Lake, Calif.,

(Granted under Title 35, US. Code (1952), sec. 266) The inventiondescribed herein may be manufactured and used by or for the Governmentof the United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

The present invention relates to novel pyrotechnics, and moreparticularly a pyrotechnic composition utiliz ing safe-to-handle azides.

In the field of pyrotechnics two criteria, rate of reaction and energyliberated per unit weight or volume, are generally of great importancein devising new pyro technics. Although many elements are and have beenused as essential ingredients of various pyrotechnics, the use of manyreactive elements such as lithium, sodium, potassium, rubidium andcesium has been severly limited because their reactivities are often toogreat. The present invention is for novel pyrotechnics the compositionof which will provide reactive species.

The general purpose of this invention is to provide a pyrotechniccomposition which has improved intensity, burning rate, color value andefficiency in light production. Also because pyrotechnic compositionsare low explosives and must withstand loading operations, handling, andstorage, other important characteristics which this invention providesare insensitivity to static, low impact and friction sensitivity, ignitibility, stability, and low hygroscopicity.

An object of the present invention is the provision of a pyrotechniccomposition which has low sensitivity to impact and is therefore safe toprepare and handle.

Another object is to provide a pyrotechnic composition which may be usedat high altitude, e.g., as an igniter or flare.

A further object of the invention'is the provision of a pyrotechniccomposition which will produce hot metallic compounds that react easilywith oxygen or a halogen.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description.

The initial work which led to the present invention was done withpurified sodium azide (NaN and potassium azide (KN intimately mixed withvarious elements including silicon, boron, aluminum, titanium,zirconium, magnesium. All ignited when touched with a hot wire. Siliconmixtures were found to ignite easily and the reaction sustained itselfto apparent completion. Aluminum and sodium azide mixtures, containingas low as 5% sodium azide ignited easier than aluminum alone and theburning sustained itself. The reaction continued at a faster rate thanthat of aluminum powder alone. As increasing quantities of sodium azidewere incorporated, faster ignition and reaction rates were realized. Totest the action in the presence of a minimum of air, a mixture of finealuminum powder and sodium azide in the ratio of 81 to 65 was packed inan open end cardboard tube 3,122,462 Patented Feb. 25, 1964 Similarreactions may be postulated for other elements. Substituting boron foraluminum in reaction (1) 186 kcal. would be produced or 1.9 kcaL/ gramcompared with 1.2 kcal./ gram for aluminum.

As a result of this work it was found feasible to prepare mixtures whichwhen ignited, would produce alkali metal vapors simply by using anexcess of alkali azide, e.g., lithium, sodium or potassium azides, andthat it was possible to produce an atmosphere of hot oxygen simply byadding to the mixture an excess of oxygen in the form ofa solid oxygencontaining oxidizer which decomposes easily at the temperatures reachedby these reactions. Oxidizers other than the oxygen containing varietymay be incorporated, e.g., halogen containing materials. The oxygenoxidizer or halogen oxidizer may be part of a polymer or plasticmaterial like Kel-F or Teflon, polyvinylidine fluoride, or copolymer ofvinylidine fluoride and perfluoropropylene or other halogen containingpolymers. Polymers containing oxidizer groups such as polynitroethylenemay be used. Examples of typical pyrotechnic formulations of thoseinvestigated are as follows:

Example 1 Percent Aluminum (Al) 49.9 Sodium azide (NaN 40.0 Potassiumpermanganate (KMnO 10.1

This mixture showed fast ignition withhot wire.

Example ll Boron (B) 29.9 Potassium azide (KN 60.1 Potassiumpermanganate (KMnO 10.0

This mixture showed rapid ignition.

Example Ill Zirconium (Zr) 68.5 Sodium azide.(NaN 16.4 Potassiumpermanganate (KMnO 15.1

This mixture exhibited rapid ignition.

Example IV Boron (B) 63.75 Sodium azide (NaN 21.25 Barium nitrate [Ba(NO15.00

, This mixture exhibited very rapid ignition.

Example V Boron (B) 71.25 Sodium azide (NaN 23.75 Potassium perchlorate(KClO 5.0

This mixture exhibited very rapid ignition.

Example VI This mixture was almost immediately explosive.

Example VIII Silicon (Si) 45 Sodium azide (NaN 45 Barium nitrate [Ba(NOThis mixture is difficult to sustain burning.

Example IX Magnesium (Mg) 45 Potassium azide (KN 45 Potassiumperchlorate (KCIO 10 This mixture is difficult to sustain burning.

Example X Boron (B) 32 Sodium azide (NaN 58 Potassium nitrate (KNO 10This mixture is fast burning.

Example XI Aluminum (Al) 45 Sodium azide (NaN 45 Potassium perchlorate(KCIO 10 This mixture is fast burning. Examples I-XI were tested at aninitial pressure of 705 mm. Hg and at ambient temperatures.

Example XII Boron (B) 27 Potassium perchlorate (KClO 10.1 Sodium azide(NaN 54.9 Binder (Viton A) 8 Example XIII Boron (B) 28.7 Potassiumperchlorate (KClO 10.7 Potassium azide (KN 57.3 Binder (Kel-F elastomer)3.3

Example XIV Boron (B) 19.0 Potassium perchlorate 6.9 Sodium azide (NaN56.1 Kel-F (powder) 12.5 Binder (Fluorel) 5.5

Example XV Magnesium (Mg) 9.6 Sodium azide (NaN 48.0 Kel-F (powder) 38.5Binder (Kel-F elastomer) 3.9

Example XVI Aluminum (Al) 38.4 Sodium azide (NaN 38.4 Kel-F (powder)19.2 Binder (Viton A) 4.0

Example XVII Boron (B) 38 Potassium azide (KN 38 Teflon powder 24 It ispostulated that the above reaction may be illustrated by the followingequation:

4 Example XVIII Percent Aluminum (Al) 38.4 Sodium azide (NaN 38.4 Binder(fluorocarbon) 23.2 Example XIX Boron (B) 26.5 Sodium azide (NaN 53.1Teflon (powder) 20.4 Example XX Zirconium (Zr) 75.1 Sodium azide (NaN18.0 Viton 6.9 Example XXI Aluminum (Al) 47.4 Sodium azide (NaN 38.0Teflon 100 9.0 Kel-F wax 5.6

In Examples XII through XXI a number of fluorocarbons were used. Amongthose found satisfactory were Viton A and AHV, Kel-F wax, Kel-Felastomer, Fluorel, Teflon, and Teflon 100.

Viton is the tradename for a rubbery copolymer of vinylidene fluorideand perfluoropropylene. Fluorel is asimilar copolymer ofperfluoropropylene and vinylidene fluoride. Teflon is the tradename fora homopolymer of tetrafluoroethylene and the same aspolytetrafluoroethylene, while Teflon 100 is a copolymer oftetrafluoroethylene and perfluoropropylene. Kel-F wax is a homopolymerof chlorotrifluoroethylene and Kel-F elastomer is a copolymer ofchlorotrifluoroethylene and vinylidene fluoride.

Examples XII-XXI not only ignited very rapidly, but burned very rapidlyas well. These mixtures are stable to fairly high temperatures, (atleast 250 C.) which increases handling safely.

An additional advantage to safety is the relative stability to impactexhibited by all the mixtures. Examples IV and VI when struck with theflat end of a hammer on a flat piece of steel were almost completelyinsensitive to such treatment. Example XV which contains no oxygenoxidizer, would not ignite or explode at all regardless of hammer force.

All these pyrotechnic samples (I-XXI) were handmixed by means of mortarand pestle. Only high temperatures above 250 C. set them olf.

Various modifications are contemplated and may obviously be resorted toby those skilled in the art without departing from the spirit and scopeof the invention as hereinafter defined by the appended claims.

What is claimed is:

1. A pyrotechnic composition consisting essentially of about 9.6 percentby weight magnesium, about 48 percent by weight sodium azide, about 38.5percent by 5 weight of a homopolymer of chlorotrifluoroethylene andabout 3.9 percent by weight of a copolymer of chlorotrifiuoroethyleneand vinylidene fluoride.

2. A pyrotechnic composition consisting essentially of about 26.5percent by weight boron, about 53.1 percent by weight sodium azide, andabout 20.4 percent by weight of a homopolymer of tetrafluoroethylene.

3. A pyrotechnic composition consisting essentially of about 75.1percent by weight zirconium, about 18 percent by weight sodium azide,and about 6.9 percent by weight of a copolymer of vinylidene fluorideand perfluoropropylene.

4. A pyrotechnic composition consisting essentially of about 47.4percent by weight aluminum, about 38 percent by weight sodium azide,about 9 percent by weight of the copolymer of tetralluoroethylcne andperfluoropropylenc and about 5.6 percent of a homopolymer ot'chlorolrifiuoroethylene.

5. A pyrotechnic composition consisting essentially of about 26 to about75 percent by weight of an element selected from the group consisting ofsilicon, boron, aluminum, titanium, zirconium and magnesium; about 18 toabout 54 percent by weight alkali azide selected from the groupconsisting of lithium, sodium and potassium azides; and about 14 toabout 42 percent by weight of a member selected from the groupconsisting of a copolymer of vinylidene fluoride and perfluoropropylene,a homopolymer of tetrafiuoroethylene, a copolymer of tetrafluoroethyleneand perfluoropropylene; a homopolymer of chlorotrifiuoroethylene, and acopolymer of chlorotrifluoroethylene and vinylidene fluoride andmixtures thereof.

References Cited in the file of this patent UNITED STATES PATENTS1,174,669 Buell Mar. 7, 1916 2,105,674 Sosson Jan. 18, 1938 2,900,242Williams et al Aug. 18, 1959 2,968,917 Whaley Jan. 24, 1961 2,981,616Boyer Apr. 25, 1961 2,995,431 Bice Aug. 8, 1961 3,027,283 Bice Mar. 27,1962

1. A PYROTECHNIC COMPOSITION CONSISTING ESSENTIALLY OF ABOUT 9.6 PERCENTBY WEIGHT MAGNESIUM, ABOUT 48 PERCENT BY WEIGHT SODIUM AZIDE, ABOUT 38.5PERCENT BY WEIGHT OF A HOMOPOLYMER OF CHLORITRIFLUOROETHYLENE AND ABOUT3.9 PERCENT BY WEIGHT OF A COPOLYMER OF CHLOROTRIFLUOROETHYLENE ANDVINYLIDENE FLUORIDE.